The invention relates to a device for manufacturing a lateral bore in a tubular bone.
For the care of bone fractures in tubular bones it is known to apply so-called locking nails. These comprise transverse bores trough which bone screws may be guided in order to hold the bone fragments on the bone nail and to secure these against displacement and torsion. Before the bone screws can be screwed in, the holes must first be drilled into the substantia corticalis, this being at a relatively exact alignment to the transverse bore in the bone nail. This nail is usually hollow. On screwing in the bone screw not only must the first facing bore be met but also the opposite lying wall of the bone nail. A wrong alignment leads possibly to the nail screw only reaching through the allocated transverse bore onto the bone nail, then however abutting against the opposite lying wall of the bone nail. In this way a satisfactory screwing or anchoring of the bone nail is not ensured.
There are numerous methods and devices which have become known in order to locate the position at which a bore for the bone screw is to be placed. Most targetting devices function according to the principle of through illumination. The operator can, on a monitor, determine the position of the transverse bore in the bone nail within the bone and correspondingly place the drill mostly after a preceding incision with a suitable drill wire or likewise. However mechanical targetting apparatus have become known which can be placed onto the free end of the bone nail. The distance of the transverse bore from the end of the bone nail is known. Also the rotational position of the transverse bore may be indicated by a suitable marking at the end of the bone nail. With the help of a suitable targetting sleeve via the targetting apparatus the substantia corticalis can be drilled. The mechanical targetting apparatus is much less complicated than the above described method which furthermore has the disadvantage that one must operate with X-rays. The mechanical targetting apparatus on the other hand has the disadvantage that a correction of the determined position of the transverse bore is not possible. Indeed it may occur that the nail on knocking in distorts and its predetermined position no longer corresponds to the actual one.